"The messages from Marine Gen. John R. Allen were uncovered by the FBI during its investigation of Petraeus last year. The tenor of some of the e-mails, which senior defense officials described as racy and flirtatious, prompted Defense Secretary Leon E. Panetta to order a formal inquiry.

"In a letter sent to Allen on Friday, the inspector general wrote that Allen had not violated military prohibitions against conduct unbecoming an officer, the senior U.S. officials said. 'He was completely exonerated,' one of the officials said."

If you need a refresher, we put together a "who's who" guide to the Petraeus scandal. Here's how we summarized Allen's involvement in the case:

"The FBI's investigation that uncovered the emails and revealed the Petraeus-Broadwell affair also led to the discovery of communications between Allen and [Jill] Kelley."

Kelley, if you remember, was the one who received emails from Paula Broadwell, the woman who was having an affair with Petraeus. She was the one who took those emails to the FBI.

NPR's Tom Bowman reports that the Inspector General found the allegations against Allen to be "unsubstantiated."

When the scandal broke, Allen's nomination to head U.S. and NATO forces in Europe was put on hold. Tom tells us that that there is no word on whether that nomination will proceed now that he's been cleared.

Earlier today, Kelley gave her first interview since the scandal broke. As Mark reported, she told The Daily Beast that she and Broadwell were not "romantic rivals" and that the number of emails she traded with Allen were in the hundreds not tens of thousands as had been originally reported.

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